Automatic coffee brewer with liquid level sensor

ABSTRACT

Cold water flows into a basin above a tank of hot water until a predetermined level is reached. A liquid level sensor then shuts off the flow of water into the basin and opens a valve to permit all of the water in the basin to flow into the tank from which the same quantity is siphoned out for brewing coffee.

United States Patent Martin I I 4 14 1 Sept. 19, 1972 AUTOMATIC-COFFEEBREWERWlTl-l LIQUID LEVEL SENSOR John c. Martin, Springfield, m.

Bunn-O-Matic Corporation, Springfield, lll.

Filed: July 6, 1971 Appl. No.: 159,767

Inventor:

Assignee:

US. Cl ..99/282 0 Int. Cl. ..A231 1/08 Field of Search ..99/280, 281,282, 283, 300,

References Cited UNITED STATES PATENTS R25,663 10/1964 I Bunn ..99/2823,179,035 4/1965 Lockett ..99/282 3,348,468 10/ 1967 Eisendrath ..99/2823,450,024

6/1969 Martin ..99/295 Primary Examiner-Robert W. JenkinsAttorney-Robert R. Lockwood [5 7] ABSTRACT Cold water flows into a basinabove a tank of hot water until a predetermined level is reached. Aliquid level sensor then shuts off the flow of water into the basin andopens a valve to permit all of the water in the basin to flow into thetank from which the same quantity is siphoned out for brewing coffee.

10 Claims, 4 Drawing Figures AUTOMATIC COFFEE BREWER WITH LIQUID LEVELSENSOR This invention relates to coffee brewing apparatus andconstitutes an improvement over the constructions disclosed in the U. S.Patent No. Re. 25,663, issued Oct. 13, 1964 and U.S. Pat. No. 3,450,024,issued June 17, i969 and in the patents and re-ferences cited therein.

Among the objects of this invention are: To provide for automaticallysupplying a predetermined quantity of water for coffee brewing purposeswithout requiring the use of a timer and independently of the watersupply pressure; to shut off the supply of cold water when the waterflowing into a basin reaches a predetermined level; to employ a liquidlevel sensor for this purpose; for the liquid level sensor to employ aprobe with an integral switching circuit; to open simultaneously a coldwater supply valve to permit water to flow into the basin and shut adump valve to preventwater from flowing out of the basin into a hotwater tank; for the dump valve to provide a length of flexible tubingthat can be pinched closed; to protect the liquid level sensor by abaffle which limits agitation of the water in its vicinity; andto'provide a baffle in the path of the incoming water to distribute ituniformly in the basin.

In the drawing:

FIG. 1 is a view, partly in cross section showing an automatic coffeebrewer embodying this invention.

FIG. 2 shows diagrammatically the circuit connections that can beemployed for the automatic coffee brewer shown in FIG. 1.

FIG. 3 illustrated diagrammatically the circuit connections that can beemployed for the liquid level sensor, the illustration showing theoperation before the water level reaches its maximum height.

FIG. 4 shows how the water level, at the predetermined height, affectsthe operation of the liquid level sensor.

In FIG. 1 reference character designates, generally, an automatic coffeebrewer embodying this invention. The automatic coffee brewer 10 includesa hot water tank 11 that may be formed of metal or of plastics material.Normally the tank 1 1 is filled with hot water 12 to the level indicatedat 13. The temperature of the water 12 is maintained by an immersionelectric heating element 14 under the control of a thermostat 15. Asindicated the arrangement is such as to supply energy to the heatingelement 14 through the thermostat 15 from a suitable current source suchas a l 15 volt 60 Hz source. A vent tube 16 extends upwardly from theupper end of the tank 11 to place it in communication with atmosphericpressure. A siphon tube 17 is employed to withdraw hot water from thetank 11 to supply it to a spray head 18 for application to ground coffee19 on a filter 20 which is located in a funnel 21. Coffee extract 22flows from the funnel 21 into a suitable receptacle as will beunderstood.

For replacing the hot water that is displaced from the tank 11 there isprovided a cold water inlet pipe 24 which may be formed of metal orplastics material. The inlet pipe 24 extends downwardly through theupper end of the tank 11 and opens near the bottom to minimize mixingwith the hot water at the upper end of the tank 1 l. The cold waterinlet pipe 24 includes a section 25 of flexible tubing which forms apart of a dump valve that is indicated, generally, at 26. The flexibletubing section 25 extends between the upper end of the inlet pipe 24 andthe bottom of a cold water basin 27 which is located above the tank 11and may be formed of metal or plastics material. Cold water is suppliedto the basin 27 through an inlet water line 28 which is connected to asource of cold water under pressure which'may vary widely. Inserted inthe inlet water line 28 is a cold water supply valve 29 which normallyis closed. Within the basin 27 there is provided a baffle 30 overlyingthe discharge or inlet end 31 of the water line 28. The purpose of thebaffle 30 is to distribute more uniformly the incoming cold water sothat it rises uniformly in the basin 27.

The dump 26 is normally open and is arranged to be closed only when coldwater is flowing into the basing 27. The dump valve 26 is arranged to beclosed by a solenoid 32 and the supply valve 29 is arranged to be openedby a solenoid 33. Normally the supply valve 29 is biased by a spring(notshown) to the closed position. Associated with the solenoid 32 is anarmature 34 which is connected to a frame 35 that surrounds the section25 of flexible tubingas shown more clearly in FIG. 2. On energization ofthe solenoid 32 the frame 35 is moved to the left to pinch the section25 of flexible tubing between it and a stationary block 36 and totension a spring 37 which is arranged to retract the frame 35 onde-energization of the solenoid 32. For each coffee brewing cycle thecold water 38 in the basin 27 is completely dumped by opening of thedump valve 26. The level 39 of the water 38 rises in the basin 27 untilit reaches a liquid level sensor that is indicated, generally, at 40 andis represented in FIG. 2 by normally closed contacts 41. In order toinsure that the level of the water 38 in the basin 27 is uniforma'baffle 42 is arranged to enclose the liquid level sensor 40. Thus itis responsive to the true level of the water 38 in the basin 27 forpreventing further inflow of cold water and for initiating the outflowof the cold water into the tank 11.

As illustrated in FIG. 2 the normally closed contacts 41 of the liquidlevel sensor 40 are connected through normally open contacts 43, whenclosed, of a relay that is indicated, generally, at 44. The relay 44 hasa winding 45. For energizing the system conductors 46 and 47 areemployed. As indicated they may be energized from a suitable 115 volt 60Hz source. A main switch 48 is arranged to connect conductor 46 toanother conductor 49 with the control system being then energizedbetween conductors 49 and 47 on closure of the main switch 48.

For initiating the brewing cycle there is provided a start switch thatis indicated, generally, at 50. When it is manually depressed contacts51 are closed to energize the winding and the solenoids 32 and 33 inparallel between the energized conductors 49 and 47. A holding circuitis then completed at contacts 43 of the relay 44 through the normallyclosed contacts 41 of the liquid level sensor 40 and through a conductor52 to the energized conductor 49. Conductors 54 and 55 connect thenormally closed contacts 41 in the circuit.

FIG. 3 illustrates the circuit details of the liquid level sensor 40which may be employed to respond to the level of the water 38 in thebasin 27. This circuit includes an SCR 56 the conductivity of which iscontrolled by a light responsive device 57 from a light source 58 whichmay be a neon lamp. Light rays, in-

alternatingcurrent to maintain and energize the wind-- ing 45 and thesolenoids 32 and 33. A diode 61 is connected across conductors 54 and 55to reduce chatter of the contacts 43 of the relay 44.

In operation the tank 11 normally is filled with hot water 12 to thelevel indicated at 13. The funnel 2l-is charged with ground coffee 19and placed in operative position under the spray head 18. After closureof main switch 48 the start switch 50 is depressed to energize winding45 of the relay 44 and the solenoids 32 and 33. After momentaryoperationof the start switch 50, the holding circuit is .completedthrough the normally closed contacts 41 and the contacts 43 of the relay44 as'described. The dump valve 26 is closed to prevent flow of any coldwater from the basin 27 into the tank 1 1 while the valve 29 is openedto permit inflow of cold water through the water line 28 into the basin27. The water level 39 rises in the basin 27 until, as shown in FIG. 4,the water level at 62 impinges upon the prism 60. Now the light rays,instead of being reflected for application to the light responsivedevice 57, are refracted as indicated at 63. The SCR 56 ceases toconduct and in effect opens the normally closed contacts 41.,Thisinterrupts the holding circuit for the winding 45 of the relay 44 andthe solenoids 32 and 33. Thereupon the previously closed dump valve 26is opened by the spring 37 and the supply valve 29 is closed. Thisprovides an accurate control of the amount of cold water 38 that issupplied to the basin 27 for the coffee brewing cycle.

By adjusting the height of the liquid level sensor 40 in the basin 27various quantities of cold water 38 can be measured as may be requireddepending upon the strength of the coffee extract 22 that is required.

I claim:

1. Coffee brewing apparatus comprising a hot water tank, means forheating water in said tank, a siphon tube for withdrawing hot water fromsaid tank to brew coffee extract, a cold water inlet pipe extendingupwardly through said tank, a dump valve in said cold water inlet pipe,a cold water basin above said hot water tank connected to said coldwater inlet pipe, an inlet water line interconnection said cold waterbasin and a source of cold water under pressure, a cold water supplyvalve in said inlet water line, means for closing said dump valve andopening said cold water supply valve to cause cold water to flowinto-said basin, and means for opening said dump valve and closing saidcold water supply valve when a predetermined quantity of cold water hasflowed into said basin.

, 2. Coffee brewing apparatus according to claim 1 wherein. meanssubstantiallysimultaneously close said an int ral switching circuit.

5. offee brewing apparatus according to claim 3 wherein said liquidlevel sensor includes normally closed switch means controlled by a lightresponsive device, a light source and a prism for directing rays fromsaid light source to said light responsive device as long as said prismis not contacted by water in said basin.

6. Coffee brewing apparatus according to claim 3 wherein a baffleencloses said liquid level sensor to permit the actual level of theliquid to be detected thereby.

7. Coffee brewing apparatus according to claim 3 wherein a baffleoverlies the discharge end of said inlet water line to distribute theincoming cold water and prevent surges thereof to contact said liquidlevel sensor.

8. Coffee brewing apparatus according to claim 1 wherein said dump valveincludes a section of flexible tubing forming a part of said cold waterinlet pipe, and means for pinching said flexible tubing.

9. Coffee brewing apparatus according to claim 1 wherein'a solenoid isarranged to operate said dump valve, another solenoid is arranged tooperate said cold water supply valve, means are connected to energizesaid solenoids through normally closed circuit means, and means opensaid normally closed circuit means when the cold water in said basinreaches a predetermined level.

10. Coffeebrewing apparatus according to claim 9 wherein said means forenergizing said solenoids includes a relay having normally open contactsconnected in series with said normally closed circuit means and anoperating winding connected in parallel with said solenoids, a manuallyoperable switch connects said winding and said solenoids forenergization to a current source, and circuit means connect saidcontacts to said current source to provide a holding circuit for saidwinding and said solenoids when said manually operable switch is opened.

1. Coffee brewing apparatus comprising a hot water tank, means forheating water in said tank, a siphon tube for withdrawing hot water fromsaid tank to brew coffee extract, a cold water inlet pipe extendingupwardly through said tank, a dump valve in said cold water inlet pipe,a cold water basin above said hot water tank connected to said coldwater inlet pipe, an inlet water line interconnection said cold waterbasin and a source of cold water under pressure, a cold water supplyvalve in said inlet water line, means for closing said dump valve andopening said cold water supply valve to cause cold water to flow intosaid basin, and means for opening said dump valve and closing said coldwater supply valve when a predetermined quantity of cold water hasflowed into said basin.
 2. Coffee brewing apparatus according to claim 1wherein means substantially simultaneously close said dump valve andopen said cold water supply valve and vice versa.
 3. Coffee brewingapparatus according to claim 1 wherein a liquid level sensor is arrangedto open said dump valve and close said cold water supply valve when thewater in said basin reaches a predetermined level.
 4. Coffee brewingapparatus according to claim 3 wherein said liquid level sensor includesa probe having an integral switching circuit.
 5. Coffee brewingapparatus according to claim 3 wherein said liquid level sensor includesnormally closed switch means controlled by a light responsive device, alight source and a prism for directing rays from said light source tosaid light responsive device as long as said prism is not contacted bywater in said basin.
 6. Coffee brewing apparatus according to claim 3wherein a baffle encloses said liquid level sensor to permit the actuallevel of the liquid to be detected thereby.
 7. Coffee brewing apparatusaccording to claim 3 wherein a baffle overlies the discharge end of saidinlet water line to distribute the incoming cold water and preventsurges thereof to contact said liquid level sensor.
 8. Coffee brewingapparatus according to claim 1 wherein said dump valve includes asection of flexible tubing forming a part of said cold water inlet pipe,and means for pinching said flexible tubing.
 9. Coffee brewing apparatusaccording to claim 1 wherein a solenoid is arranged to operate said dumpvalve, another solenoid is arranged to operate said cold water supplyvalve, means are connected to energize said solenoids through normallyclosed circuit means, and means open said normally closed circuit meanswhen the cold water in said basin reaches a predetermined level. 10.Coffee brewing apparatus according to claim 9 wherein said means forenergizing said solenoids includes a relay having normally open contactsconnected in series with said normally closed circuit means and anoperating winding connected in parallel with said solenoids, a manuallyoperable switch connects said winding and said solenoids forenergization to a current source, and circuit means connect saidcontacts to said current source to provide a holding circuit for saidwinding and said solenoids when said manually operable switch is opened.